Ullage

About: Ullage is a research topic. Over the lifetime, 501 publications have been published within this topic receiving 4704 citations. The topic is also known as: headspace.

Studying Flammability in a Commercial Transport Fuel Tank with Inerting

Abstract: As part of the continued emphasis on fuel tank safety, the Federal Aviation Administration (FAA) has developed a demonstration fuel tank inerting system and has tested it on a NASA -operated Boeing 747 aircraft. To support this, the FAA developed two models to predict both fuel tank oxygen concentration and flammability in an inerted ullage, based on pre viously developed models and calculations. Laboratory and aircraft test results indicated that the models duplicated measured data trends well and gave predicted peak values with a reasonable degree of accuracy. This allowed the FAA to develop a repr esentative Boeing 747 aircraft flight cycle and give predictions of flammability exposure for the given ullage. The results indicated that the aircraft fuel tank would not be exposed to flammable conditions during the developed flight profile with the represented inerting system even though part of the tank ullage did achieve oxygen concentration levels of approximately 18%.

Fuel tank ullage purge system

Abstract: A purge system includes an airflow source to provide an airflow, and a fuel tank, including: a tank volume including a tank ullage, at least one inlet, wherein the at least one inlet is in fluid communication with the tank ullage and the airflow source to provide the airflow as an inbound airflow to the tank ullage, and at least one outlet, wherein the at least one outlet is in fluid communication with the tank ullage and an overboard location outside the aircraft to direct the inbound airflow as an outbound airflow from the tank ullage to the overboard location.

Risk assessment and mitigation for the hazards of electromagnetic radiation to fuel during high intensity radiated field testing of aircraft

Abstract: High Intensity Radiated Field (HIRF) testing of, in, and around, aircraft, and aircraft subsystems, that contain fuel (or other potentially explosive atmosphere creating substances) pose particular hazards for Radio Frequency (RF) Induced ignition — Hazards of Electromagnetic Radiation to Fuel (HERF). The primary threat is considered to be from ignition by RF induced sparking/arcing, as this requires far less energy than direct heating effects. Accepted international guidance that is used is contained in “CENELEC CLC/TR 50427: Assessment of Inadvertent Ignition of Flammable Atmospheres by Radio-Frequency Radiation” to identify risks posed by the testing. Where hazardous levels of RF energy are identified as being used within a HIRF test, various mitigations can be used to reduce the overall risk, such as: Air frame/fuel-system review and/or inspection to reduce the probability of any dormant or undetected make/break arcing mechanisms within the flammable atmosphere/ullage; read-across of Electrostatic Discharge (ESD)/Lightning Strike design protection measures that would make the risk non-credible; specifying a minimum fuel load so arcing mechanisms are not in ullage space; use of alternate fuels to change the fuel/air mixture in the ullage to being too rich or too lean; injection of inert atmospheres into the ullage to prevent ignition; identification of alternate assessment strategies and/or potential restriction on HIRF test levels, to identify safe and cost effective assessment solutions for aircraft HIRF clearance activities.

Atmospheric heating of vessels

Abstract: A design method is presented which predicts the maximum operating temperature of storage vessels exposed to atmospheric and solar heating containing liquefied gases, permanent gases or liquids. It is used to calculate the design pressure and/or minimum ullage of such vessels and will be published as an Australian Standard. The paper includes design curves and the derivation of some novel thermodynamic quantities.

Cryogenic liquid storage tank includes an ullage tank disposed within main tank and has opening where pipe segment is connected

Abstract: The tank (10) comprises of main tank (12) for receiving liquid via fill pipe (22) Ullage tank (30) disposed within main tank and has opening (32) where pipe segment (36) is connected for conveying liquid between bottom of ullage to top of main tank Pipe segment has effective flow rate less than fill pipe such that ullage tank does not fill with liquid unit after main tank is filled and empties faster than main tank as liquid is dispensed from main tank due to pressure differential between tanks